Effects of Na 2 O and K 2 O on liquidus temperatures in ZnO–‘FeO’–Al 2 O 3 –CaO–SiO 2 system in equilibrium with metallic iron

The phase equilibria in the ZnO–‘FeO’–Al₂O₃–CaO–SiO₂–Na₂O (K₂O) system have been determined experimentally in equilibrium with metallic iron. Pseudoternary sections ZnO–‘FeO’–(Al₂O₃+CaO+SiO₂) for CaO/SiO₂ = 0·71 (weight), (CaO+SiO₂)/Al₂O₃ = 5·0 (weight) and fixed Na₂O or K₂O content have been constructed. It has been found that the addition of 1·0 wt-%Na₂O or K₂O does not introduce any new primary phases in the composition range investigated. The presence of 1·0 wt-%Na₂O or K₂O in the liquid phase extends the wustite primary phase field and reduces the size of the spinel primary phase field. Liquidus temperatures are slightly increased in the wustite primary phase field and decreased in the spinel primary phase field by addition of 1·0 wt-%Na₂O or K₂O. Neither Na₂O nor K₂O is detected in the wustite or spinel solid solutions. The presence of 1·0 wt-%Na₂O or K₂O in the slag does not affect the partitioning of the ZnO between the solid (wustite or spinel) and liquid phases.